The present invention relates as indicated to winder drums for strip slitting lines, and relates more particularly to winder drums so constructed and arranged that the strips are wound tight on the drums regardless of the difference in thickness or gauge between the strips to be wound on the drums.
A problem universally recognized in the winding of strip material, for example strip steel, is the inability to uniformly wind the several strips onto the winder drums due to the lack of uniformity in thickness of the formed strips. Frequently, the original, relatively wide, steel strip from which the strips are slit is crowned, that is, it tapers from a greatest thickness at the transverse center of the strip to a thinner gage at the marginal portions of the strip. Thus, unless the thickness differences are compensated for, the marginal strips do not build up in the same uniform manner as the strips slit from the center portion of the plate, thereby resulting in loose strips corresponding to the strips formed at the marginal portions of the original, wide strip. Since it is highly desirable to wind or build up the strips into relatively tight coils on the drums, resort has been made to fillers of various types, including special cardboard, or the like, which are manually inserted into the marginal strips in order to avoid loosely hanging strips and to provide the desired tight buildup of the strip on the drum. This procedure is not only highly labor-consuming but also physically dangerous to the workers, and the presence of fillers in the coiled strips presents certain disadvantages to the ultimate consumer.
In recognition of such problem, there have been numerous attempts in the prior art to provide apparatus for coiling slit strips with uniform tension, with most of these devices being mainly concerned with the winding of paper and plastic strip material. Due to the vastly greater forces involved in the winding of strip steel, most of the prior art devices for winding paper and plastic are inadequate. The winding devices in the prior art for winding metallic strip are extremely complicated and are frequently limited to a particular strip width.
Reference will now be made to known prior art devices for tensioning slit strip material, with such art, however, not fully satisfying the problems referred to above. U.S. Pat. No. 3,061,226 to V. J. Kegg discloses a device for applying extra tension to the marginal metal strips but is applicable only to relatively small coils. One known example of the inability of the Kegg device to handle large coils is an instance in which the loose strips for a large coil hung down 15 feet, representing 30 feet of loose strip. Moreover, the rollers which supply such additional tension to the strips have to be changed in accordance with the width of the strips, and the device has the further disadvantage that it needs a relatively expensive collapsible coiler.
U.S. Pat. No. 3,853,280 to Joseph V. Pennisi et al. discloses a winding mandrel which compensates for unequal thicknesses in the material by imposing a limiting torque condition on each core. However, the disclosed apparatus is for the particular purpose of winding pressure-sensitive adhesive tape wherein very low tension conditions exist, and the construction of the mandrel is such that it would not be satisfactory for winding individual steel strips with uniform tension.
U.S. Pat. No. 3,878,999 to Howard W. Daves also discloses winding apparatus for maintaining equal winding tension of a plurality of strips wound simultaneously on individual cores. However, the mandrel is comprised of individual sections each of which is independently contained and actuated, and the device is limited to certain fixed size strip widths, or multiples thereof.
Other prior art known to applicant alluding generally to the problems outlined above are U.S. Pat. Nos. 3,188,016 to C. Aaron; 3,552,672 to Karl E. L. Grettve; 3,592,405 to Michael M. Young and 3,817,468 to Albert E. Smolderen et al. However, these relating to winding devices primarily designed for winding paper or plastic material, or are structurally quite dissimilar from the present invention.